/Engine/Source/Runtime/GeometryFramework/Public/Components/MeshRenderDecomposition.h
Build per-material decomposition, and then split each of those into chunks of at most MaxChunkSize (actual chunk sizes will be highly variable and some may be very small...)
static void BuildChunkedDecomposition ( const [FDynamicMesh3](API\Runtime\GeometryCore\DynamicMesh\FDynamicMesh3) * Mesh, const [FComponentMaterialSet](API\Runtime\InteractiveToolsFramework\TargetInterfaces\FComponentMaterialSet) * MaterialSet, [FMeshRenderDecomposition](API\Runtime\GeometryFramework\Components\FMeshRenderDecomposition) & Decomp, int32 MaxChunkSize )